This invention relates to a method and apparatus for controlling the operation of an internal combustion engine of a motor vehicle in order to achieve optimum fuel efficiency.
It is customary to control the driving power of a motor vehicle internal combustion engine by modification of the supply of fuel to the engine, for example, by influencing the control of a fuel metering device, such as the throttle flap in a carburetor or the injection quantity per stroke in a fuel injected diesel engine. Within the limits of engine operating parameters, it is usually left to the driver to determine what gear should be used and what accelerator pedal position will be set for any particular operating situation. Since only a defined power of the engine is available at each engine rotational speed for optimum engine fuel efficiency, this manner of operation oftern leads to unnecessarily high fuel consumption.
In U.S. Pat. No. 3,916,854, there is described an apparatus wherein the position of a throttle valve is not directly controlled by movement of the accelerator pedal. The throttle valve is only allowed to reach a position which is predetermined by means of a cam connected to a governor, so that during the running-up of the engine, the engine accelerates along a curve with a view to minimal fuel consumption for attainment of maximum power at all engine rotational speeds. Following attainment of the selected throttle valve position, in accordance with the accelerator pedal setting, the operating point travels over a curve of more unfavorable consumption, corresponding to a constant throttle valve setting, according to the position of the accelerator pedal, until the traction resistance curve is reached.
It is an object of the present invention to provide a method and apparatus for providing more efficient operation of a motor vehicle by the use exclusively of a preselected curve in the power-speed diagram which connects the operating points of maximum power at predetermined fuel consumption.